Rogers blames Russians

4/21/13 11:48 AM EDT

The FBI did a "very thorough job" of checking out Tamerlan Tsarnaev after being tipped off to his potential extremism, the chairman of the House Intelligence Committee said on Sunday, blaming Russia for failing to provide any further information.

"It's important to understand why the FBI interviewed him in the first place: They were concerned about his possible radicalization," Rep. Mike Rogers (R-Mich.) said on NBC’s “Meet the Press,” adding the FBI did a “ very thorough job” trying to run that into the ground. “And then [the FBI] asks [for] some more help from that intelligence service to try to get further clarification."

He said Tsarnaev started his radicalization in the United States, then continued it during his trip to Russia last year, when he spent six months there. Rogers said he believes Tsarnaev used an alias to travel.

"When he comes back he has a renewed interest in that radicalization belief process…. He's very devout," Rogers said. "You see something happening and you can see it happening after that travel, and so that 6-1/2 months becomes incredibly important."

Rogers said the question still remains of whether Tsarnaev may have received some type of training there.